[16a-PA06-1~13] 3.7 Optical measurement, instrumentation, and sensor (formerly 3.8)

[16a-PA06-12] Establishment of Discrimination Method between Artificial Structure and Defect in Appearance Defect Inspection with Phase Shift Illumination Method

〇Yoshito Onishi¹, Yoshiho Seo¹, Masaoki Matsuoka², Shigeru Serikawa³, Ken Tsugane² (1.Hitachi, Ltd., 2.Hitachi High-Tech Corporation, 3.Hitachi High-Tech Solutions Corporation)

Keywords:Defect inspection, Phase-shift-illumination approach

To improve the recognition accuracy in automatic inspection, we developed the optical-engineering and image-processing technologies to enhance unclear defects in transparent material with the phase-shift illumination approach. Our challenge has been the discrimination of actual defects from dark fringes due to artificial textures for optical performance or design. We proposed that the artificial textures with gentler slope should be more insensitive than actual defects by providing the illumination pattern with finite-width dark regions such as the rectangular-wave illumination. Experimentally and theoretically, we confirmed that the rectangular-wave illumination enables us to selectively distinguish between defects and artificial textures.